536 lines
18 KiB
C
536 lines
18 KiB
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* AEAD: Authenticated Encryption with Associated Data
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*
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* Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
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*/
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#ifndef _CRYPTO_AEAD_H
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#define _CRYPTO_AEAD_H
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#include <linux/crypto.h>
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#include <linux/kernel.h>
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#include <linux/slab.h>
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/**
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* DOC: Authenticated Encryption With Associated Data (AEAD) Cipher API
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*
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* The AEAD cipher API is used with the ciphers of type CRYPTO_ALG_TYPE_AEAD
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* (listed as type "aead" in /proc/crypto)
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*
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* The most prominent examples for this type of encryption is GCM and CCM.
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* However, the kernel supports other types of AEAD ciphers which are defined
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* with the following cipher string:
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*
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* authenc(keyed message digest, block cipher)
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*
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* For example: authenc(hmac(sha256), cbc(aes))
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*
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* The example code provided for the symmetric key cipher operation
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* applies here as well. Naturally all *skcipher* symbols must be exchanged
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* the *aead* pendants discussed in the following. In addition, for the AEAD
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* operation, the aead_request_set_ad function must be used to set the
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* pointer to the associated data memory location before performing the
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* encryption or decryption operation. In case of an encryption, the associated
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* data memory is filled during the encryption operation. For decryption, the
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* associated data memory must contain data that is used to verify the integrity
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* of the decrypted data. Another deviation from the asynchronous block cipher
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* operation is that the caller should explicitly check for -EBADMSG of the
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* crypto_aead_decrypt. That error indicates an authentication error, i.e.
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* a breach in the integrity of the message. In essence, that -EBADMSG error
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* code is the key bonus an AEAD cipher has over "standard" block chaining
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* modes.
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*
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* Memory Structure:
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*
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* To support the needs of the most prominent user of AEAD ciphers, namely
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* IPSEC, the AEAD ciphers have a special memory layout the caller must adhere
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* to.
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*
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* The scatter list pointing to the input data must contain:
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*
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* * for RFC4106 ciphers, the concatenation of
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* associated authentication data || IV || plaintext or ciphertext. Note, the
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* same IV (buffer) is also set with the aead_request_set_crypt call. Note,
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* the API call of aead_request_set_ad must provide the length of the AAD and
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* the IV. The API call of aead_request_set_crypt only points to the size of
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* the input plaintext or ciphertext.
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*
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* * for "normal" AEAD ciphers, the concatenation of
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* associated authentication data || plaintext or ciphertext.
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*
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* It is important to note that if multiple scatter gather list entries form
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* the input data mentioned above, the first entry must not point to a NULL
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* buffer. If there is any potential where the AAD buffer can be NULL, the
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* calling code must contain a precaution to ensure that this does not result
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* in the first scatter gather list entry pointing to a NULL buffer.
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*/
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struct crypto_aead;
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/**
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* struct aead_request - AEAD request
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* @base: Common attributes for async crypto requests
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* @assoclen: Length in bytes of associated data for authentication
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* @cryptlen: Length of data to be encrypted or decrypted
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* @iv: Initialisation vector
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* @src: Source data
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* @dst: Destination data
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* @__ctx: Start of private context data
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*/
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struct aead_request {
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struct crypto_async_request base;
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unsigned int assoclen;
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unsigned int cryptlen;
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u8 *iv;
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struct scatterlist *src;
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struct scatterlist *dst;
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void *__ctx[] CRYPTO_MINALIGN_ATTR;
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};
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/**
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* struct aead_alg - AEAD cipher definition
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* @maxauthsize: Set the maximum authentication tag size supported by the
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* transformation. A transformation may support smaller tag sizes.
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* As the authentication tag is a message digest to ensure the
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* integrity of the encrypted data, a consumer typically wants the
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* largest authentication tag possible as defined by this
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* variable.
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* @setauthsize: Set authentication size for the AEAD transformation. This
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* function is used to specify the consumer requested size of the
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* authentication tag to be either generated by the transformation
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* during encryption or the size of the authentication tag to be
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* supplied during the decryption operation. This function is also
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* responsible for checking the authentication tag size for
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* validity.
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* @setkey: see struct skcipher_alg
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* @encrypt: see struct skcipher_alg
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* @decrypt: see struct skcipher_alg
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* @ivsize: see struct skcipher_alg
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* @chunksize: see struct skcipher_alg
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* @init: Initialize the cryptographic transformation object. This function
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* is used to initialize the cryptographic transformation object.
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* This function is called only once at the instantiation time, right
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* after the transformation context was allocated. In case the
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* cryptographic hardware has some special requirements which need to
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* be handled by software, this function shall check for the precise
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* requirement of the transformation and put any software fallbacks
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* in place.
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* @exit: Deinitialize the cryptographic transformation object. This is a
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* counterpart to @init, used to remove various changes set in
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* @init.
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* @base: Definition of a generic crypto cipher algorithm.
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*
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* All fields except @ivsize is mandatory and must be filled.
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*/
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struct aead_alg {
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int (*setkey)(struct crypto_aead *tfm, const u8 *key,
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unsigned int keylen);
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int (*setauthsize)(struct crypto_aead *tfm, unsigned int authsize);
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int (*encrypt)(struct aead_request *req);
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int (*decrypt)(struct aead_request *req);
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int (*init)(struct crypto_aead *tfm);
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void (*exit)(struct crypto_aead *tfm);
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unsigned int ivsize;
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unsigned int maxauthsize;
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unsigned int chunksize;
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struct crypto_alg base;
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};
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struct crypto_aead {
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unsigned int authsize;
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unsigned int reqsize;
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struct crypto_tfm base;
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};
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static inline struct crypto_aead *__crypto_aead_cast(struct crypto_tfm *tfm)
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{
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return container_of(tfm, struct crypto_aead, base);
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}
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/**
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* crypto_alloc_aead() - allocate AEAD cipher handle
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* @alg_name: is the cra_name / name or cra_driver_name / driver name of the
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* AEAD cipher
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* @type: specifies the type of the cipher
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* @mask: specifies the mask for the cipher
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*
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* Allocate a cipher handle for an AEAD. The returned struct
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* crypto_aead is the cipher handle that is required for any subsequent
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* API invocation for that AEAD.
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*
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* Return: allocated cipher handle in case of success; IS_ERR() is true in case
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* of an error, PTR_ERR() returns the error code.
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*/
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struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask);
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static inline struct crypto_tfm *crypto_aead_tfm(struct crypto_aead *tfm)
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{
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return &tfm->base;
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}
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/**
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* crypto_free_aead() - zeroize and free aead handle
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* @tfm: cipher handle to be freed
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*/
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static inline void crypto_free_aead(struct crypto_aead *tfm)
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{
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crypto_destroy_tfm(tfm, crypto_aead_tfm(tfm));
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}
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static inline struct aead_alg *crypto_aead_alg(struct crypto_aead *tfm)
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{
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return container_of(crypto_aead_tfm(tfm)->__crt_alg,
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struct aead_alg, base);
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}
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static inline unsigned int crypto_aead_alg_ivsize(struct aead_alg *alg)
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{
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return alg->ivsize;
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}
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/**
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* crypto_aead_ivsize() - obtain IV size
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* @tfm: cipher handle
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*
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* The size of the IV for the aead referenced by the cipher handle is
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* returned. This IV size may be zero if the cipher does not need an IV.
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*
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* Return: IV size in bytes
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*/
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static inline unsigned int crypto_aead_ivsize(struct crypto_aead *tfm)
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{
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return crypto_aead_alg_ivsize(crypto_aead_alg(tfm));
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}
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/**
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* crypto_aead_authsize() - obtain maximum authentication data size
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* @tfm: cipher handle
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*
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* The maximum size of the authentication data for the AEAD cipher referenced
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* by the AEAD cipher handle is returned. The authentication data size may be
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* zero if the cipher implements a hard-coded maximum.
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*
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* The authentication data may also be known as "tag value".
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*
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* Return: authentication data size / tag size in bytes
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*/
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static inline unsigned int crypto_aead_authsize(struct crypto_aead *tfm)
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{
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return tfm->authsize;
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}
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/**
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* crypto_aead_blocksize() - obtain block size of cipher
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* @tfm: cipher handle
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*
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* The block size for the AEAD referenced with the cipher handle is returned.
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* The caller may use that information to allocate appropriate memory for the
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* data returned by the encryption or decryption operation
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*
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* Return: block size of cipher
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*/
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static inline unsigned int crypto_aead_blocksize(struct crypto_aead *tfm)
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{
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return crypto_tfm_alg_blocksize(crypto_aead_tfm(tfm));
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}
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static inline unsigned int crypto_aead_alignmask(struct crypto_aead *tfm)
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{
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return crypto_tfm_alg_alignmask(crypto_aead_tfm(tfm));
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}
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static inline u32 crypto_aead_get_flags(struct crypto_aead *tfm)
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{
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return crypto_tfm_get_flags(crypto_aead_tfm(tfm));
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}
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static inline void crypto_aead_set_flags(struct crypto_aead *tfm, u32 flags)
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{
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crypto_tfm_set_flags(crypto_aead_tfm(tfm), flags);
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}
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static inline void crypto_aead_clear_flags(struct crypto_aead *tfm, u32 flags)
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{
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crypto_tfm_clear_flags(crypto_aead_tfm(tfm), flags);
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}
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/**
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* crypto_aead_setkey() - set key for cipher
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* @tfm: cipher handle
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* @key: buffer holding the key
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* @keylen: length of the key in bytes
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*
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* The caller provided key is set for the AEAD referenced by the cipher
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* handle.
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*
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* Note, the key length determines the cipher type. Many block ciphers implement
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* different cipher modes depending on the key size, such as AES-128 vs AES-192
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* vs. AES-256. When providing a 16 byte key for an AES cipher handle, AES-128
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* is performed.
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*
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* Return: 0 if the setting of the key was successful; < 0 if an error occurred
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*/
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int crypto_aead_setkey(struct crypto_aead *tfm,
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const u8 *key, unsigned int keylen);
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/**
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* crypto_aead_setauthsize() - set authentication data size
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* @tfm: cipher handle
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* @authsize: size of the authentication data / tag in bytes
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*
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* Set the authentication data size / tag size. AEAD requires an authentication
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* tag (or MAC) in addition to the associated data.
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*
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* Return: 0 if the setting of the key was successful; < 0 if an error occurred
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*/
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int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize);
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static inline struct crypto_aead *crypto_aead_reqtfm(struct aead_request *req)
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{
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return __crypto_aead_cast(req->base.tfm);
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}
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/**
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* crypto_aead_encrypt() - encrypt plaintext
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* @req: reference to the aead_request handle that holds all information
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* needed to perform the cipher operation
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*
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* Encrypt plaintext data using the aead_request handle. That data structure
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* and how it is filled with data is discussed with the aead_request_*
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* functions.
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*
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* IMPORTANT NOTE The encryption operation creates the authentication data /
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* tag. That data is concatenated with the created ciphertext.
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* The ciphertext memory size is therefore the given number of
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* block cipher blocks + the size defined by the
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* crypto_aead_setauthsize invocation. The caller must ensure
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* that sufficient memory is available for the ciphertext and
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* the authentication tag.
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*
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* Return: 0 if the cipher operation was successful; < 0 if an error occurred
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*/
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static inline int crypto_aead_encrypt(struct aead_request *req)
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{
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struct crypto_aead *aead = crypto_aead_reqtfm(req);
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struct crypto_alg *alg = aead->base.__crt_alg;
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unsigned int cryptlen = req->cryptlen;
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int ret;
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crypto_stats_get(alg);
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if (crypto_aead_get_flags(aead) & CRYPTO_TFM_NEED_KEY)
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ret = -ENOKEY;
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else
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ret = crypto_aead_alg(aead)->encrypt(req);
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crypto_stats_aead_encrypt(cryptlen, alg, ret);
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return ret;
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}
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/**
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* crypto_aead_decrypt() - decrypt ciphertext
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* @req: reference to the ablkcipher_request handle that holds all information
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* needed to perform the cipher operation
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*
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* Decrypt ciphertext data using the aead_request handle. That data structure
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* and how it is filled with data is discussed with the aead_request_*
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* functions.
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*
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* IMPORTANT NOTE The caller must concatenate the ciphertext followed by the
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* authentication data / tag. That authentication data / tag
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* must have the size defined by the crypto_aead_setauthsize
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* invocation.
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*
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*
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* Return: 0 if the cipher operation was successful; -EBADMSG: The AEAD
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* cipher operation performs the authentication of the data during the
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* decryption operation. Therefore, the function returns this error if
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* the authentication of the ciphertext was unsuccessful (i.e. the
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* integrity of the ciphertext or the associated data was violated);
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* < 0 if an error occurred.
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*/
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static inline int crypto_aead_decrypt(struct aead_request *req)
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{
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struct crypto_aead *aead = crypto_aead_reqtfm(req);
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struct crypto_alg *alg = aead->base.__crt_alg;
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unsigned int cryptlen = req->cryptlen;
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int ret;
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crypto_stats_get(alg);
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if (crypto_aead_get_flags(aead) & CRYPTO_TFM_NEED_KEY)
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ret = -ENOKEY;
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else if (req->cryptlen < crypto_aead_authsize(aead))
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ret = -EINVAL;
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else
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ret = crypto_aead_alg(aead)->decrypt(req);
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crypto_stats_aead_decrypt(cryptlen, alg, ret);
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return ret;
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}
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/**
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* DOC: Asynchronous AEAD Request Handle
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*
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* The aead_request data structure contains all pointers to data required for
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* the AEAD cipher operation. This includes the cipher handle (which can be
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* used by multiple aead_request instances), pointer to plaintext and
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* ciphertext, asynchronous callback function, etc. It acts as a handle to the
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* aead_request_* API calls in a similar way as AEAD handle to the
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* crypto_aead_* API calls.
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*/
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/**
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* crypto_aead_reqsize() - obtain size of the request data structure
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* @tfm: cipher handle
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*
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* Return: number of bytes
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*/
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static inline unsigned int crypto_aead_reqsize(struct crypto_aead *tfm)
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{
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return tfm->reqsize;
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}
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/**
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* aead_request_set_tfm() - update cipher handle reference in request
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* @req: request handle to be modified
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* @tfm: cipher handle that shall be added to the request handle
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*
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* Allow the caller to replace the existing aead handle in the request
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* data structure with a different one.
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*/
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static inline void aead_request_set_tfm(struct aead_request *req,
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struct crypto_aead *tfm)
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{
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req->base.tfm = crypto_aead_tfm(tfm);
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}
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/**
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* aead_request_alloc() - allocate request data structure
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* @tfm: cipher handle to be registered with the request
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* @gfp: memory allocation flag that is handed to kmalloc by the API call.
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*
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* Allocate the request data structure that must be used with the AEAD
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* encrypt and decrypt API calls. During the allocation, the provided aead
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* handle is registered in the request data structure.
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*
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* Return: allocated request handle in case of success, or NULL if out of memory
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*/
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static inline struct aead_request *aead_request_alloc(struct crypto_aead *tfm,
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gfp_t gfp)
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{
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struct aead_request *req;
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req = kmalloc(sizeof(*req) + crypto_aead_reqsize(tfm), gfp);
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if (likely(req))
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aead_request_set_tfm(req, tfm);
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return req;
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}
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/**
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* aead_request_free() - zeroize and free request data structure
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* @req: request data structure cipher handle to be freed
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*/
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static inline void aead_request_free(struct aead_request *req)
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{
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kzfree(req);
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}
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/**
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* aead_request_set_callback() - set asynchronous callback function
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* @req: request handle
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* @flags: specify zero or an ORing of the flags
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* CRYPTO_TFM_REQ_MAY_BACKLOG the request queue may back log and
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* increase the wait queue beyond the initial maximum size;
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* CRYPTO_TFM_REQ_MAY_SLEEP the request processing may sleep
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* @compl: callback function pointer to be registered with the request handle
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* @data: The data pointer refers to memory that is not used by the kernel
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* crypto API, but provided to the callback function for it to use. Here,
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* the caller can provide a reference to memory the callback function can
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* operate on. As the callback function is invoked asynchronously to the
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* related functionality, it may need to access data structures of the
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* related functionality which can be referenced using this pointer. The
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* callback function can access the memory via the "data" field in the
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* crypto_async_request data structure provided to the callback function.
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*
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* Setting the callback function that is triggered once the cipher operation
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* completes
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*
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* The callback function is registered with the aead_request handle and
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* must comply with the following template::
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*
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* void callback_function(struct crypto_async_request *req, int error)
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*/
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static inline void aead_request_set_callback(struct aead_request *req,
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u32 flags,
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crypto_completion_t compl,
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void *data)
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{
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req->base.complete = compl;
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req->base.data = data;
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req->base.flags = flags;
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}
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/**
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* aead_request_set_crypt - set data buffers
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* @req: request handle
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* @src: source scatter / gather list
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* @dst: destination scatter / gather list
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* @cryptlen: number of bytes to process from @src
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* @iv: IV for the cipher operation which must comply with the IV size defined
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* by crypto_aead_ivsize()
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*
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* Setting the source data and destination data scatter / gather lists which
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* hold the associated data concatenated with the plaintext or ciphertext. See
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* below for the authentication tag.
|
|
*
|
|
* For encryption, the source is treated as the plaintext and the
|
|
* destination is the ciphertext. For a decryption operation, the use is
|
|
* reversed - the source is the ciphertext and the destination is the plaintext.
|
|
*
|
|
* The memory structure for cipher operation has the following structure:
|
|
*
|
|
* - AEAD encryption input: assoc data || plaintext
|
|
* - AEAD encryption output: assoc data || cipherntext || auth tag
|
|
* - AEAD decryption input: assoc data || ciphertext || auth tag
|
|
* - AEAD decryption output: assoc data || plaintext
|
|
*
|
|
* Albeit the kernel requires the presence of the AAD buffer, however,
|
|
* the kernel does not fill the AAD buffer in the output case. If the
|
|
* caller wants to have that data buffer filled, the caller must either
|
|
* use an in-place cipher operation (i.e. same memory location for
|
|
* input/output memory location).
|
|
*/
|
|
static inline void aead_request_set_crypt(struct aead_request *req,
|
|
struct scatterlist *src,
|
|
struct scatterlist *dst,
|
|
unsigned int cryptlen, u8 *iv)
|
|
{
|
|
req->src = src;
|
|
req->dst = dst;
|
|
req->cryptlen = cryptlen;
|
|
req->iv = iv;
|
|
}
|
|
|
|
/**
|
|
* aead_request_set_ad - set associated data information
|
|
* @req: request handle
|
|
* @assoclen: number of bytes in associated data
|
|
*
|
|
* Setting the AD information. This function sets the length of
|
|
* the associated data.
|
|
*/
|
|
static inline void aead_request_set_ad(struct aead_request *req,
|
|
unsigned int assoclen)
|
|
{
|
|
req->assoclen = assoclen;
|
|
}
|
|
|
|
#endif /* _CRYPTO_AEAD_H */
|